The electroluminescent device has beneficial properties, such as active luminescence, wider visual angle, higher contrast, high response speed and so on, and is praised as a new generation of display techniques. According to the materials employed for the luminescent layer, the electroluminescent device is classified as inorganic electroluminescent device and organic electroluminescent device. When the luminescent layer contacting with the moisture in the air, the performance and life of the luminescent layer within the electroluminescent device would be deteriorated, thus it is required to isolate the luminescent layer from the moisture in the air. FIG. 1 illustrates an organic electroluminescent device 1 comprising a base substrate 2, the base substrate 2 is provided thereon with an anode electrode 3, a cathode electrode 5 and a luminescent layer 4 located between the anode electrode 3 and cathode electrode 5, as well as a sealing element 6 for sealing the base substrate 2 onto which the sealing element 6 is attached with an adhesives 7, and a first substrate 8 used for packaging. The sealing element 6 may be a cover glass, or an insulating board or an insulating film. The entire side surface 61 of the sealing element 6 contacts with air, thus due to resultant larger contact area, the moisture in the air at the side surface of the sealing element may pass through the adhesives and into the sealing element 6, contact with the luminescent layer, which deteriorates the performance and life of the luminescent layer in the electroluminescent device.